That depends on how much flight time you have.
You could start with 40% on the low rate and 60% on the high rate. Start on low rate & see how it goes, switch to high rates when you are ready. When you are ready for more, bump it up to 50 & 70, keep increasing the rates slowly until you want to stop.
Expo is a matter of personal choice, it’s like having low rates near the center of the stick and high rates on the ends of stick movement. My preference is 30-40% expo. Some like more some less. Like rates, it’s best to start low and work higher. Just for grins, while on the ground, set the expo @ 100% & move the sticks. You will have nothing until you get near the end, then bang, you get full throw. Not good.